Recently, there has been some work on removing redundant reference count operations in the Python interpreter. The following paper describes how it can be done:

Recently, there has been some work on removing redundant reference count operations in the Python interpreter. The following paper describes how it can be done: http://portal.acm.org/citation.cfm?id=1869631.1869633 http://portal.acm.org/citation.cfm?id=1869631.1869633. Regarding the performance impact of reference counting, the following facts are important: - Switching from immediate reference counting to deferred reference counting (L.P. Deutsch and D.G. Bobrow, 1976 [1]) eliminates about 90pct of all reference count operations in Smalltalk (Berkeley Smalltalk '82, that is) [2] - A very good account of reference counting can be found in either Dave Ungar's excellent PhD thesis [3] and Dave Ungar and Dave Patterson's in-depth analysis of Smalltalk performance [4]. [1] An efficient, incremental, automatic garbage collector (http://www.cs.umass.edu/~emery/classes/cmpsci691s-fall2004/papers/p522-deutsch.pdf http://www.cs.umass.edu/~emery/classes/cmpsci691s-fall2004/p...) [2] High performance storage reclamation in an object-based memory system (http://techreports.lib.berkeley.edu/accessPages/CSD-84-167.html http://techreports.lib.berkeley.edu/accessPages/CSD-84-167.h...) [3] The Design and Evaluation of A High Performance Smalltalk System (http://www.eecs.berkeley.edu/Pubs/TechRpts/1986/5376.html http://www.eecs.berkeley.edu/Pubs/TechRpts/1986/5376.html) [4] Berkeley Smalltalk: Who knows where the time goes? (Chapter 11 of http://www.iam.unibe.ch/~ducasse/FreeBooks/BitsOfHistory/ http://www.iam.unibe.ch/~ducasse/FreeBooks/BitsOfHistory/)